The disclosure of Japanese Patent Application No. HEI 9-338846 filed on Dec. 9, 1997 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to an air bag apparatus for a passenger seat for protecting an occupant in the passenger seat in a vehicle such as a motor vehicle and the like.
2. Description of the Related Art
A known air bag apparatus for a passenger seat is described in, for example, Japanese Patent Application Laid-open No. Hei 7-215151.
In conjunction with the air bag apparatus for a passenger seat, the laid-open patent application proposes an air bag folding manner such that the air bag will be deployed toward an occupant""s torso during an early period of deployment. Furthermore, in this air bag apparatus for a passenger seat, the resistance or drag that occurs when the air bag is unfolded from the folded state is utilized to reduce the deploying speed of the air bag.
However, in a typical air bag apparatus for a passenger seat, the air bag needs to be tightly folded in order to minimize the size of the entire apparatus. Therefore, there is a danger that at the time of an impact on the vehicle, the air bag may not completely unfold but may remain partially folded or packed when an occupant moves forward by inertia and contacts the air bag. Also, in a typical air bag arrangement, gas is directly jetted into the air bag from the inflator, so that it is difficult to control the direction of gas flow in the air bag. Therefore, it is difficult to control the direction of deployment of the air bag.
Accordingly, it is an object of the present invention to provide a passenger seat air bag arrangement having a reduced deploying speed.
According to a first aspect of the invention, there is provided an air bag apparatus for a passenger seat disposed in a passenger seat-side instrument panel. The air bag apparatus includes an air bag folded and disposed in a case having at one side thereof an opening, and an inner bag disposed in the air bag so that the inner bag is inflated prior to inflation of the air bag. The inner bag is designed to press a portion of the air bag against at least one of a front glass pane and an instrument panel when inflated.
With this construction, the air bag is inflated and deployed, dragging between the inner bag and the front glass pane and/or between the inner bag and the instrument panel. Sliding friction that occurs at the dragging portions reduces the deploying speed of the air bag with respect to conventional air bag arrangements. Therefore, even if an occupant comes into contact with the air bag before the deployment is completed (during the deployment), the air bag will not strongly contact the occupant.
One alternative construction features providing a supply hole in the inner bag for supplying gas to the air bag.
This construction makes it possible to adjust the deploying speed of the air bag by suitably selecting the size and number of supplying holes formed in the inner bag.
According to an alternative construction, the inner bag may be designed to press a portion of the air bag against each of the front glass pane and the instrument panel. The air bag is inflated and deployed, dragging between the inner bag and the front glass pane and between the inner bag and the instrument panel. Sliding friction that occurs on the dragging portions further reduces the deploying speed of the air bag. According to another alternative construction, the inner bag may have an upper inflating portion and a lower inflating portion. The upper inflating portion is formed so as to inflate to a greater size than the lower inflating portion.
This optional construction ensures that a large area of the inner bag presses against the front glass pane even if the front glass pane is far apart from the instrument panel. Therefore, the deploying speed of the upper portion of the air bag can be effectively reduced.
According to an alternative construction, a restriction member may be disposed in the inner bag. The restriction member restricts inflation of a central portion of the inner bag to a predetermined amount and defines, at least partially, two inflating portions in the inner bag.
This construction enhances the pressing of the inner bag against the front glass pane and the instrument panel, thereby more reliably reducing the deploying speed of the air bag.
The inner bag may be formed by sewing an upper face to a lower face cloth. The upper face cloth is inflated and deployed in an upward direction relative to the vehicle. The lower face cloth is inflated and deployed in a downward direction relative the vehicle.
This construction ensures that the upper face cloth will press a portion of the air bag against the front glass pane and the lower face cloth will press another portion of the air bag against the instrument panel. Therefore, the deploying speed of the air bag can be reliably reduced.
The restriction member may extend from an end of at least one of the upper face cloth and the lower face cloth. This construction facilitates production of the inner bag.
The restriction member may be disposed in the inner bag at a lower position therein so that an upward deploying portion of the inner bag is inflated and deployed to a greater size than a downward deploying portion of the inner bag.
This construction ensures that the upper face cloth will press a portion of the air bag against the front glass pane, thereby reliably reducing the deploying speed of the air bag.
The inner bag may be formed by two base cloths so that when the inner bag is inflated and deployed, the base cloths face each other in transverse directions relative to the vehicle and the inner bag is inflated and deployed in upward and downward directions relative to the vehicle.
This construction makes it possible to sufficiently inflate and deploy the inner bag in the upward and downward directions relative to the vehicle and therefore reduce the deploying speed of the air bag, without requiring a restriction member or the like that is disposed in the inner bag for restricting the amount of inflation of a central portion of the inner bag. Therefore, the structure of the inner bag can be simplified.
The inner bag may assume a generally gourd shape in a side view when it is inflated. With this construction, when the inner bag is inflated and deployed, the tensions on the bag portions of the inner bag repel each other at a constricted portion therebetween and therefore resist collapse in vertical directions. Therefore, the inner bag continues pressing portions of the air bag against the front glass pane and the instrument panel until the inflating deployment of the bag 32 is completed. Consequently, the deploying speed of the air bag will be more effectively reduced.
The inner bag may contact the front glass pane and the instrument panel so as to curve into a generally crescent shape in a side view when it is inflated. When the inner bag contacts the front glass pane and the instrument panel, gas pressure inside the inner bag urges the inner bag to inflate into a designed deployment shape, so that the force of the inner bag pressing against the front glass pane and the instrument panel is increased. Since the sliding friction caused on portions of the air bag that drag between the inner bag and the front glass pane and between the inner bag and the instrument panel is also increased, the deploying speed of the air bag will be more effectively reduced.
The inner bag may have an extension portion that extends in a rearward direction relative to the vehicle. The extension portion presses a portion of the air bag against the instrument panel. The extension portion actively presses a portion of the air bag against the instrument panel, so that a portion of the air bag will be reliably sandwiched between the extension portion and the instrument panel. Therefore, the deploying speed of the air bag will be reliably reduced.
The inner bag may have a forward ejection hole for ejecting gas in a forward direction relative to the vehicle.
With this construction, when the inner bag is inflated, the air bag is deployed also in the forward direction by gas supplied through the forward ejection hole. Therefore, a forward portion of the air bag is additionally pressed against the front glass pane and the instrument panel by gas supplied thereinto. Consequently, the sliding resistance occurring when the air bag is deployed is further increased, thereby further reducing the deploying speed of the air bag.
During assembly of the air bag apparatus, before it is put into its case, the air bag may be folded by folding portions of the air bag that face in forward and rearward directions relative to the vehicle and then folding portions of the air bag that face in transverse directions relative to the vehicle.
This construction enables smooth inflation and deployment of the air bag in the transverse directions relative to the vehicle. Furthermore, since the portions of the air bag that face in forward and rearward directions relative to the vehicle are folded before the portions of the air bag that face in transverse directions relative to the vehicle are folded, the air bag is deployed in the transverse directions prior to the deployment in the fore-to-aft directions. Therefore, the deploying speed of the air bag toward the occupant side is further reduced.
The inner bag may be folded by folding opposite end portions thereof that face in the transverse directions relative to the vehicle while avoiding folding a central portion of the air bag relative to the case, in the transverse directions.
During an early period of deployment of the air bag, the entire folded portions facing in the fore-to-aft directions are quickly protruded from the upper surface of the instrument panel as the inner bag is inflated and deployed. Therefore, the air bag is inflated and deployed more smoothly in the transverse directions, so that the deploying speed of the air bag toward the occupant side will be reliably reduced.
An inflator having a cylindrical shape may be disposed so that an axis thereof extends substantially in a fore-to-aft direction relative to the vehicle.
During an early period of deployment of the air bag, the entire folded portions of the air bag facing in the fore-to-aft directions are reliably protruded from the upper surface of the instrument panel as the inner bag is inflated and deployed. Therefore, the deploying speed of the air bag toward the occupant side will be more reliably reduced.
A portion of the air bag may be disposed between an inner wall face of the case and right and left sides of the inflator. This construction enables compact packaging of the air bag in the case.
The air bag apparatus for a passenger seat may be constructed to include a fixing portion at which the air bag is fixed to the case and a mouth portion that guides gas into the air bag. The mouth portion is disposed in a central portion of the case. An upward deploying portion of the air bag and a downward deploying portion of the air bag are folded and disposed in a space between the mouth portion and one of opposite inner surfaces of the case that face the mouth portion and a space between the mouth portion and the other one of the opposite inner surfaces of the case, respectively.
This construction enables compact packaging of the air bag in the case while improving the deploying performance of the air bag.
An air bag cover may be disposed at the opening of the case. The air bag cover can be opened in transverse directions relative to the vehicle in a manner of a double-hinged door.
With this construction, the air bag cover will not interfere with the inflating deployment of the inner bag and the air bag toward the occupant side. Furthermore, this construction reliably prevents the cover from contacting an occupant when the cover breaks open.
The air bag apparatus can be constructed to include an outlet hole for exhausting gas, and the inner bag has a supply hole for supplying gas to the air bag. The air bag and the inner bag are disposed in the case in such a manner that the outlet hole of the air bag and the supply hole of the inner bag correspond to each other, and so that, during inflation of the inner bag and the air bag, the supply hole and the outlet hole become separate from each other.
With this construction, during an early period of the deployment of the inner bag, gas introduced into the inner bag flows out through the supply hole of the inner bag and through the outlet hole of the air bag, so that the gas pressure inside the inner bag decreases and, therefore, the deploying speed of the inner bag also decreases. Therefore, if an occupant contacts the air bag and presses the inner bag during the deployment of the inner bag, the inflation of the air bag afterwards is weakened, thereby substantially preventing strong contact of the air bag with the occupant.
According to the first aspect of the invention, the outlet hole of the air bag and the supply hole of the inner bag may be sewed together at peripheral portions thereof so as to correspond to each other, using a thread that breaks when the air bag and the inner bag are inflated.
With this construction, during an early period of the deployment of the inner bag, gas flows out of the inner bag through the supply hole of the inner bag and through the outlet hole of the air bag without fail, so that the gas pressure inside the inner bag reliably decreases and, therefore, the deploying speed of the inner bag reliably decreases. Therefore, even if an occupant contacts the air bag and thus presses the inner bag during an early period of the deployment of the inner bag, strong contact of the inner bag with the occupant will be substantially prevented.
A site in the inner bag and a site in the air bag that come closest to an occupant side at the time of completion of inflation and deployment of the inner bag and the air bag may be interconnected so that the sites remain interconnected during an early period of the inflation of the inner bag and the air bag, and so that the sites are disconnected from each other as the inner bag and the air bag are further inflated.
The interconnection between the aforementioned sites reduces the deploying speed of the air bag toward the occupant side. Therefore, even if at the time of a vehicle crash, an occupant moves forward and comes into contact with the air bag before it is completely deployed, strong contact of the air bag with the occupant will be prevented.
A second aspect of the invention provides an air bag apparatus for a passenger seat disposed in a passenger seat-side instrument panel. The air bag apparatus includes an air bag having an outlet hole for exhausting gas. The air bag is folded and disposed in a case having at one side thereof an opening. The inner bag has a supply hole for supplying gas to the air bag. The inner bag is disposed in the air bag so that the inner bag is inflated prior to inflation of the air bag. The air bag and the inner bag are disposed in the case in such a manner that the outlet hole of the air bag and the supply hole of the inner bag correspond to each other. During inflation of the inner bag and the air bag, the supply hole and the outlet hole become separate from each other.
Early during deployment of the inner bag, gas introduced into the inner bag flows out through the supply hole of the inner bag and through the outlet hole of the air bag, so that the gas pressure inside the inner bag decreases and, therefore, the deploying speed of the inner bag also decreases. Therefore, if an occupant contacts the air bag and presses the inner bag during the deployment of the inner bag, the inflation of the air bag afterwards is weakened, thereby substantially preventing strong contact of the air bag with the occupant.
In this second aspect of the invention, the outlet hole of the air bag and the supply hole of the inner bag may be sewed together at peripheral portions thereof so as to correspond to each other, using a thread that breaks when the air bag and the inner bag are inflated.
With this construction, during an early period of deployment of the inner bag, gas flows out of the inner bag through the supply hole of the inner bag and through the outlet hole of the air bag without fail, so that the gas pressure inside the inner bag reliably decreases and, therefore, the deploying speed of the inner bag reliably decreases. Therefore, even if an occupant contacts the air bag and thus presses the inner bag during an early period of the deployment of the inner bag, strong contact of the inner bag with the occupant will be substantially prevented.
The inner bag may be provided with a duct extending therefrom corresponding to the supply hole. In this case, the inner bag and the air bag are folded and disposed in the case in such a manner that the duct protrudes out from the outlet hole of the air bag.
With this construction, there is no need to sew a peripheral portion of the supply hole of the inner bag to a peripheral portion of the outlet hole of the air bag. Therefore, the production efficiency of the air bag apparatus for a passenger seat can be improved.
As a construction alternative, a site in the inner bag and a site in the air bag that come closest to an occupant side at the time of completion of inflation and deployment of the inner bag and the air bag may be interconnected so that the sites remain interconnected during an early period of the inflation of the inner bag and the air bag, and so that the sites are disconnected from each other as the inner bag and the air bag are further inflated.
The interconnection between the aforementioned sites reduces the deploying speed of the air bag toward the occupant side. Therefore, even if at the time of a vehicle crash, an occupant moves forward and comes into contact with the air bag before it is completely deployed, strong contact of the air bag with the occupant will be prevented.
According to a third aspect of the invention, there is provided an air bag apparatus for a passenger seat disposed in a passenger seat-side instrument panel. The air bag apparatus includes an air bag folded and disposed in a case having at one side thereof an opening, and an inner bag disposed in the air bag so that the inner bag is inflated prior to inflation of the air bag. A site in the inner bag and a site in the air bag that come closest to an occupant side at the time of completion of inflation and deployment of the inner bag and the air bag are interconnected so that the sites remain interconnected during an early period of the inflation of the inner bag and the air bag, and so that the sites are disconnected from each other as the inner bag and the air bag are further inflated.
The interconnection between the aforementioned sites reduces the deploying speed of the air bag toward the occupant side. Therefore, even if at the time of a vehicle crash, an occupant moves forward and comes into contact with the air bag before it is completely deployed, strong contact of the air bag with the occupant will be prevented.
The inner bag has a supply hole for supplying gas to the air bag. This construction makes it possible to adjust the deploying speed of the air bag by suitably selecting the size and number of supplying holes.
A site in the inner bag and a site in the air bag that come closest to an occupant side at the time of completion of inflation and deployment of the inner bag and the air bag may be interconnected by a restriction member that is folded and sewed with a breakable thread so that the folded sections of the restriction member are joined together.
With this construction, during an early period of the deployment of the air bag, the deploying direction of the air bag is restricted by the restriction member after the breakable thread joining the folded sections thereof breaks.
The interconnected sites in the inner bag and the air bag may be directly sewed together using a thread that breaks when the inner bag and the air bag are inflated.
This construction reduces the deploying speed of the air bag without requiring a complicated arrangement. Furthermore, during an early period of the deployment of the air bag, since the deploying direction of the air bag is restricted by the site connected to the inner bag, the air bag is stably inflated and deployed.